The broad aims of the project are (1) to determine the characteristic biochemical composition of photoreceptor, neuronal, glial and pigmented epithelial cells (with emphasis on rod outer segment membranes); (2) to identify and assess the usefulness of biochemical marker substances (or ratios of substances) as quantitative indices of certain histological entities or metabolic routes in retinal tissues; (3) to use indices in conjunction with other chemical constituents and enzymes to study retinal tissues (and vision-related regions of brain) in normal, experimentally-induced and heritable pathological conditions.